Cells or capsules containing electronic ink react to voltages placed on them and are used for generating images. A capsule may typically include white and black electronic ink particles. The ink is reactive and moves in accordance with the voltage applied to the capsule or cell. To change image content on an electrophoretic electronic ink display, new image information is written for a certain amount of time (e.g., 500 ms-1000 ms). As the refresh rate of an active-matrix is usually higher, this results in addressing the same image content during a number of frames (e.g., at a frame rate of 50 Hz, 25 to 50 frames).
Referring to FIG. 1, a schematic drawing of the electronic -ink capsule 12 is illustratively shown. Addressing of electronic ink from black to white, for example, requires pixel capacitor plates 10a and 10b to be charged to −15 V during a 500 ms to 1000 ms interval. During this time the white particles drift towards the top (common) electrode, while the black particles drift towards the bottom (active-matrix back plane) electrode. Switching to black requires a positive pixel voltage. At 0 V on the pixel capacitor the electronic ink does not switch.
These display arrangements often include complex processing steps. With each generation of active matrix display, increased processing complexity of the active matrix is experienced, which has a negative influence on the price. For example, the semiconductor is the most expensive layer in an active matrix backplane and the costs may exceed around ∈620 per display for materials alone.
Therefore, a need exists to reduce both material cost and processing complexity in active matrix displays.